引起Ⅰ型变态反应的抗体（）
A.IgG抗体
B.IgM抗体
C.两者均可
D.两者均否
参考答案：D
DVD-9
Generally speaking, when the Herfindahl-Hirschman Index (HHI) is calculated by summing the squared percentage market shares, how many largest firms data is used in a industry, supposing there is a large number of firms in the industry:（）
A．4
B．10
C．50
